The long-term objective of this part of the proposal is to isolate ant-tumor and other bioactive compounds from microalgae, especially those in the lower eukaryotic phyla of Protocista. The proposed work is based on the promising results obtained in the preceding grant period. Discovered and anticipated compounds are macrolides, polyethers, polyoxygenated alkyl compounds, nitrogenous compounds, etc., whose structural types are not seen in other phyla. There are strong indications that some of the highly active trace compounds discovered in marine supply of such compounds from culturable sources. The project leader's group has lengthy experience in culturing microalgae and studying their metabolites and is in possession of a large culture collection and excellent facilities. Specifically, 1. Free-living microalgae belong to Pyrrophyta, Haptophyta, Cryptophyta and Raphidophyta from both temperate and tropical waters and some from inland waters will be cultured in quantity and screened for bioactivities. 2. Organisms symbiotic or associated with marine invertebrates, macro- and microalgae will be isolated, cultured and screened. In particular, the hitherto unculturable organisms known to produce interesting metabolites and have intra-cellular symbionts, such as Cryptophyta organisms in Dinophysis spp., will be focused. 3. Crude, partially purified and pure compounds will be tested in mechanism-based assays at Bristol-Myers Squibb, and their structures will be studied using various physico-chemical methods. Limited in- house cytotoxicity and mechanism-based assays will be performed as quick isolation guides. The structures of pure active compounds will be elucidated by physico-chemical methods including high field NMR. 4. Large-scale culture work will be done using the recently developed facilities to produce enough amounts of compounds with proven activity.